Arrange the following in order of decreasingbond angles (i)CH_(4), NH_(3), H_(2)O, BF_(3), C_(2) H_(2) ""(ii) NH_(3), NH_(2)^(-), NH_(4) ^(+)

Arrange the following in order of decreasingbond angles (i)CH_(4), NH_

1.	Arrange the following in order of decreasingbond angles (i)CH_(4), NH_(3), H_(2)O, BF_(3), C_(2) H_(2) ""(ii) NH_(3), NH_(2)^(-), NH_(4) ^(+)
Answer» Solution : (i) `C_(2) H_(2) (180^(@)) gt CH_(4) (109^(@) 28') gtBF_(3) (120^(@)) gt nh_(3) (107^(@)) gt H_(2) O gt (104.5^(@))`. (ii) ` NH_(4)^(+) gt NH_(3) gt NH_(2)^(-)` This is because all of them involve `sp^(3)`hybridization . The NUMBER of lone pair of electrons presnt on N- atom are 0,1 and 2 resprectively. Greater the number of lone pairs, greater are the REPULSIONS on the bond pairs and HENCE smaller is the angle .